1. Field of the Invention
The present invention relates to an electrophotographic image forming apparatus, a process cartridge, a developing device, and a developer frame.
An electrophotographic image forming apparatus forms an image on a recording medium by using the electrophotographic image forming process. An example of the electrophotographic image forming apparatus includes an electrophotographic copying machine, an electrophotographic printer (e.g., a laser beam printer or LED printer), a facsimile device, and a word processor.
A process cartridge is comprised of charging means, developing means or cleaning means, and an electrophotographic photosensitive drum that are integrally formed into a cartridge, which is detachably mountable in an electrophotographic image forming apparatus main body. Alternatively, a process cartridge is comprised of at least one of charging means, developing means, and cleaning means, and an electrophotographic photosensitive drum that are integrally formed into a cartridge, which is detachably mountable in an electrophotographic image forming apparatus main body. Alternatively, a process cartridge is comprised of at least developing means and an electrophotographic photosensitive drum that are integrally formed into a cartridge, which is detachably mountable in an electrophotographic image forming apparatus main body.
2. Description of the Related Art
An electrophotographic image forming apparatus using the electrophotographic image forming process employs a process-cartridge method in which an electrophotographic photosensitive member and process means that acts on the electrophotographic photosensitive drum are integrally formed into a cartridge, and the cartridge is detachably mountable in an electrophotographic image forming apparatus main body. According to the process-cartridge method, since the apparatus can be maintained by the user himself or herself without asking for a person in charge of maintenance, the operability can be greatly improved. For this reason, the process-cartridge method is widely used in the field of electrophotographic image forming apparatus.
Some electrophotographic image forming apparatuses employing the process-cartridge method have developer amount detecting means for informing the user that the developer is consumed, so that the user can exchange the cartridge by himself, as described above. One developer amount detecting means employs a method of detecting the developer amount by detecting a change in capacitance between electrodes arranged in the process cartridge.
Regarding the arrangement of the electrodes, an arrangement in which an electrode rod is arranged at a predetermined distance from a developer bearing member and the capacitance between the electrode rod and the developer bearing member is detected, an arrangement in which opposing electrode plates are arranged at positions between which the developer can enter and the capacitance between the electrode plates is detected, and an arrangement as a combination of the above two arrangements are available.
Each one of the developer amount detecting means described above detects a change in capacitance caused by the amount of developer which enters between the electrodes. Thus, the detection precision is largely influenced by the circulation of the developer.
The present invention is made by further developing the related art described above.
It is an object of the present invention to provide an electrophotographic image forming apparatus, a process cartridge, a developer container, and a developing device, in which a developer can be circulated and supplied in an optimal manner between electrodes constituting developer amount detecting means, which detects the developer amount by detecting a change in capacitance between the electrodes.
It is another object of the present invention to provide a developing device, a developer container, a process cartridge, and an electrophotographic image forming apparatus in which the developer amount can be detected with a high precision.
It is still another object of the present invention to provide, in a process cartridge detachably mountable in an electrophotographic image forming apparatus main body, a developing device, a developer container, a process cartridge, and an electrophotographic image forming apparatus, comprising an electrophotographic photosensitive member, developing means for developing a latent image formed on the electrophotographic photosensitive member by using a developer, a developer frame for containing the developer which visualizes the latent image formed on the electrophotographic photosensitive member and supplying the developer to the developing means through an opening, a first electrode, and a second electrode provided in a direction of the developer frame to oppose the first electrode, wherein the first and second electrodes are arranged at such positions that the developer can enter therebetween, and a capacitance between the second and first electrodes, which is generated when a voltage is applied to the second electrode, is detected, thereby detecting the developer amount, and the developer frame is arranged such that a lower end portion thereof on an upper side of the opening is above a lower end of the second electrode.
It is still another object of the present invention to provide an electrophotographic image forming apparatus, a process cartridge, a developing device, or a developer container, in which an unstable substance other than a developer is prevented from being present between electrodes, so that a developer amount detection error is minimized.
It is still another object of the present invention to provide, in a process cartridge detachably mountable in an electrophotographic image forming apparatus main body, a process cartridge, a developing device, a developer container, and an electrophotographic image forming apparatus, comprising an electrophotographic photosensitive member, developing means for developing a latent image formed on the electrophotographic photosensitive member by using a developer, a developer frame for containing the developer which visualizes the latent image formed on the electrophotographic photosensitive member and supplying the developer to the developing means through an opening, a seal member attached to the developer frame and adapted to close the opening of the developer frame, thereby sealing the developer, a first electrode, and a second electrode provided in a direction of the developer frame to oppose the first electrode. The first and second electrodes are arranged at such positions that the developer can enter therebetween, and a capacitance between the second and first electrodes, which is generated when a voltage is applied to the second electrode, is detected, thereby detecting the developer amount. The seal member is removed leaving an attached portion thereof which is attached to the developer frame, so that the opening is unsealed and the developer can be supplied to the developing means. The attaching portion of the seal member on an upper side, which is left after unsealing, is above a lower end of the second electrode.
These and other objects, features and advantages of the present invention will become more apparent upon consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings.